Controlled frequency signals
In some embodiments, a transmitter includes first encoding controlled frequency output circuitry to creates a magnitude encoded controlled frequency signal (CFS) and second encoding controlled frequency output circuitry to create a complementary a magnitude encoded controlled frequency signal (CCFS). Other embodiments are described and claimed.
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The present application and application Ser. No. 10/225,691 entitled “Receivers for Controlled Frequency Signals” were filed on the same day, have essentially identical specifications, and claim related subject matter.
BACKGROUND OF THE INVENTION1. Technical Field of the Invention
The inventions relate to transmitters and receivers that provide and receive controlled frequency signals and systems including such transmitters and receivers.
2. Background Art
Inter symbol interference (ISI) degrades signal integrity through superimposition of pulses at varying frequencies. Data patterns with high frequency pulses are susceptible to ISI. Higher frequency pulses may phase shift more and attenuate more relative to lower frequency pulses leading to loss of the higher frequency pulses when superimposed with lower frequency pulses. The distortion to data patterns caused by ISI may lead to errors. The frequency at which uncompensated random data patterns in conventional signaling can be transmitted may be limited by ISI.
Equalization and Nyquist signaling are two solutions to ISI that have been proposed. Equalization is a curve-fitting solution that attempts to restore amplitude for higher frequency pulses in susceptible data patterns. It seeks to anticipate lost data and restore it through pre-emphasizing the amplitude on narrow pulses. Disadvantages of equalization include that it is at best a curve fitting solution, tweaking the amplitude of higher frequency pulses in random pulses of data to restore any anticipated loss in amplitude. The anticipated loss is very system specific and pattern specific, thus requiring tuning for predicted data patterns and for each custom system it is used in. It is susceptible to unpredicted data patterns and varying system transfer functions. The iterative nature of such solutions results in time-consuming and system-specific implementations, possibly never converging to optimal solutions.
Nyquist Signaling is another prior art solution for ISI, which uses a raised cosine or sinc function pulses in the time domain to overcome ISI. The complexity to implement such functions is prohibitive in practice.
In source synchronous signaling, data signals and one or more associated clock or strobe signals are sent from a transmitter to a receiver. The clock or strobe signal is used by the receiving circuit to determine times to sample the data signals.
In some signaling techniques, timing information can be embedded into the transmitted data signal and recovered through a state machine. An interpolator receives a number of clock or strobe signals from, for example, a phase locked loop or a delayed locked loop. The recovered timing is used to select among or between the clock or strobe signals received by the interpolator and provide the selected clock or strobe signal to a receiver to control sampling of the incoming data signal. In some implementations, training information is provided in the data signal to get the proper sample timing before actual data is transmitted. The training information can be provided from time to time to keep the sample timing. In other implementations, training information is not used, but the sample timing is created from the data signals of prior time. There are various techniques for embedding timing information. The 8B/10B technique is a well known technique.
The transmission of signals may be in a multi-drop (one transmitter to multiple receivers) or point-to-point (one transmitter to one receiver). The transmission may be uni-directional, sequential bi-direction, or simultaneous bi-directional.
Noise on signals on conductors may cause the signals to be corrupted. A technique to reduce the effect of noise is to transmit the data on two wires and then reject the noise in the receiver by looking at the difference between the received signals rather than the absolute values. Typically, one conductor carries a signal that is the inverse of the other conductor.
The inventions will be understood more fully from the detailed description given below and from the accompanying drawings of embodiments of the inventions which, however, should not be taken to limit the inventions to the specific embodiments described, but are for explanation and understanding only.
In some embodiments, the inventions described herein include a system having a transmitter that encodes a data signal into a magnitude encoded controlled frequency signal (CFS). In some embodiments, a complementary magnitude encoded controlled frequency signal (CCFS) is also created. The voltage of CFS is VCFS and the voltage of CCFS is VCCFS.
Referring to
In
1. Transmitters.
There are a variety of ways in which the transmitters of
A clock signal (Clk) is carried on a conductor 102, an inverse of Clk (Clk*) is carried on a conductor 104, an input signal (Vin) is carried on a conductor 106, and an inverse input signal (Vin*) is carried on conductor 108. As can be seen, in
There are a variety of encoding techniques that can be used in connection with the CFS and CCFS. Examples of the encoding techniques include in phase magnitude encoding (“In Phase Encoding”), power balanced magnitude encoding (“Power Balanced Encoding”), and offset balanced magnitude encoding (“Offset Balanced Encoding”). Examples of these three encoding techniques in response to three or four of the Clk, Clk*, Vin, and Vin* signals of
In
In
In
In
Accordingly, the voltage of CFS is a function of the inputs to drivers 158, 202, and 204. For example, if the inputs to drivers 158, 202, and 204 are each a logical 1 voltage, each of drivers 158, 202, and 204 is pulling to VDD, and CFS on conductor 24A is pulled to VDD. Likewise, if the inputs are each a logical 0 voltage, then CFS is pulled to VSS. When one of the inputs to drivers 158, 202, and 204 is a logical 1 voltage and two inputs are logical 0 voltage, CFS is pulled to ⅓ VDD. When two of the inputs to drivers 158, 202, and 204 are logical 1 voltages and one input is a logical 0 voltage, CCFS is pulled to ⅔ VDD. (The inventions are not limited to these details. For example, drivers 158, 202, and 204 could invert the input value.)
Table 1 shows the outputs of NOR gate 210 and NAND gate 212 as a function of Clk and Vin. The outputs of gates 210 and 212 are the inputs of drivers 202 and 204, respectively. The table also shows the output of inverter, 156 (which is the input of driver 158), and a value of CFS as a function of the outputs of driver 158 and first and second encode drivers 202 and 204.
Of course, the full high voltage signal is not necessarily exactly at VDD, the medium low voltage signal is not necessarily exactly at ⅓ VDD, the medium high voltage signal is not necessarily exactly at ⅔ VDD, and the full low signal is not necessarily exactly at VSS.
The transmitter 20 in
The combination of CFS and CCFS allows good signal integrity at higher frequencies of data transmission by canceling noise and facilitating decoding. The signals also inherently carry some immunity to (ISI). Merely as an example, a mathematical model of magnitude encoded controlled frequencies is provided in equation (1), which shows a Fourier transform as follows:
s(t)=(B+E·m[trunc(t/2ω0)])cos ω0t+VDD/2⇄S(ω)=(B+α·E)δ(ω0)+C (1)
where t is time, s(t) is a function in the time domain, ω is frequency, ω0 is a control frequency (a frequency the data is encoded at), m is an array of encoded digital values (comprising data pattern), B is a constant value for base, E is a constant value for encode high, VDD is a supply voltage, S(ω) is the function in the frequency domain, α is a ratio of 1s to 0s in m, δ(ω0) is an impulse function, and C is a constant DC offset. The impulse function in the frequency domain, with data encoded on it, yields the benefits of eliminating or substantially reducing ISI since all or substantially all of the energy of the signal is restricted to a single frequency. The inventions are not limited to the details of equation (1).
2. Receivers.
Receivers 28 . . . 30 and 48 . . . 50 in
Clock deriving circuitry 188 may also provide a derived clock* signal, which is an inverse of the derived clock signal (for example, like Clk and Clk* of
a. Receivers for Decoding CFS and CCFS Created by In Phase Encoding and Power Balanced Encoding.
The voltage swing on conductors 24A and 24B is not necessarily the same as the voltage swing in receiver 28. For ease of discussion, the power supply and ground voltages on conductors 24A and 24B are referred to as Vdd and Vss (see
Averaging circuitry 240 is formed of amplifiers 234 and 236, nodes N1, N2, and N3, and resistors 238 and 240, which each have a resistance value R1. Resistors 238 and 240 each may be, for example, formed of an N-type field effect transistor (NFET) and a p-type field effect transistor (PFETs) (such as transistors T11 and T13 in
The term “inverse” is used herein in the context of Clk and Clk* being logical inverses, Vin and Vin* being logical inverses, and Vout and Vout* being logical inverses. In this context, inverse means that if Clk is a logical 0 voltage, then Clk* is a logical 1 voltage and if Clk is a logical 1 voltage, then Clk* is a logical 0 voltage. (Of course, a logical 0 voltage is not necessarily at VSS and a logical 1 voltage is not necessarily at VDD). The same is the case with Vin and Vin* and Vout and Vout*.
Reference inverting circuitry 244 provides a reference inverse of VN2 on node N4. Reference inverting circuitry 244 includes a first inverter including PFET T2 and NFET T3, a second inverter including PFET T6 and NFET T7, and enabling transistors T1, T4, T5, and T8. The term “reference inverse” for VN2 and VN4 is a little more relaxed than the term “inverse” in that VN2 and VN4 are not necessarily within either normal logical 0 or 1 voltages (although they could be within normal logical 0 or 1 voltages). With the reference inverse, VN2 and VN4 are on opposite sides of a reference voltage. For example, in operation, if VN2 is greater than the reference voltage, then VN4 is less it, and if VN2 is less than the reference voltage, then VN4 is greater than it. The precise value of the reference voltage is not important and there is not necessarily a single reference voltage. The reference voltage may be a narrow band of voltages the boundaries of which can change over time.
In the case of In Phase Encoding,
If VCFS is Vss and VCCFS is ⅓ Vdd (see
If VCFS is Vdd and VCCFS is ⅔ Vdd (see
If VCFS is ⅓ Vdd and VCCFS is Vss (see
In the case of Power Balanced Encoding,
If VCFS is ⅔ Vdd and CCFS is Vss (see
If VCFS is ⅓ Vdd and CCFS is Vdd (see
If VCFS is Vdd and CCFS is ⅓ Vdd (see
The beta's of each of the transistors may be the same. However, by having transistors T1, T4, T5, and T8 have a smaller beta than for the transistors of the inverters, superior level shifting from Vdd and Vss to VDD and VSS may occur and the gain may be flatter.
b. Receivers for Decoding CFS and CCFS Created by Offset Balanced Encoding.
Referring to MECF decoder 184 of
In the case in which Vin is a logical 0 voltage, VCFS and VCCFS are within the high and low thresholds (t0+X to t2+X in
If VCFS<VCCFS, then derived clock is a logical 0 voltage and derived clock* is logical 1 voltage so that T20 and T23 are off and T21 and T22 are on. CCFS is passed to the negative input of comparator 324 and CFS is passed to the negative input of comparator 326. With VCCFS<high threshold, the output of comparator 324 is a logical 1 voltage. With VCFS>low threshold, the output of comparator 326 is logical 0 voltage. Therefore, comparator 328 outputs Vout as a logical 0 voltage which matches Vin for to t0 t1 in
In the case in which Vin is a logical 1 voltage, VCFS and VCCFS are outside the high and low thresholds (t2+X to t5+X in
3. Additional Information and Embodiments.
As described above, there are advantages to using both the CFS and CCFS signals in combination to convey information. However, the information can be conveyed in the CFS alone. (Recall that in
The inventions are not limited to a particular type of interconnect between the transmitter and receiver circuitry. For example, the illustrated versions of the transmitters and receivers show the interconnects as being electrical conductors that carry conventional electrical signals. However, various other types of interconnects could be used including electromagnetic interconnects (for example, waveguides (including fiber optics) and radio-frequency (RF)). Merely as an example,
Conductors 24A and 24B are not necessarily continuous but could include intermediate circuitry, vias etc. The conductors may include capacitors for AC coupling although that may slow the switching speed.
The inventions may be used in point-to-point interconnect systems as shown in
The transmitters and receivers are illustrated in terms of encoding merely logical 0 or 1 voltages for CFS and CCFS. Alternatively, more than two logical values could be encoded in CFS and CCFS. For example, referring to
The inventions are not limited to a particular type, format, content, or meaning for CFS and CCFS being transmitted. In some embodiments, some conductors carrying commands, while others carry address, and others carry data. In some embodiments, commands, address, and data are provided in a multiplexed signal. In some embodiments, commands may be carried through transmitters and receivers using different signaling. Various encoding techniques such as 8b/10b encoding may be used with the encoding techniques described herein. The illustrated circuits are merely examples. The polarities of the various signals may change.
The illustrated circuitry may include additional circuitry such as electrostatic discharge (ESD) circuitry, enable signal control circuitry, and timing chains. In alternative embodiments, the CFS could be carried differentially on two conductors and CCFS could be carried differentially on two conductors.
There are various ways in which the Clk, Clk*, Vin, and Vin* signals may be produced.
The term “responsive” means one thing or event at least partially causes another thing or event, although there may be other causes for the thing or event.
An embodiment is an implementation or example of the inventions. Reference in the specification to “an embodiment,” “one embodiment,” “some embodiments,” or “other embodiments” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least some embodiments, but not necessarily all embodiments, of the inventions. The various appearances “an embodiment,” “one embodiment,” or “some embodiments” are not necessarily all referring to the same embodiments.
If the specification states a chip, feature, structure, or characteristic “may”, “might”, or “could” be included, that particular chip, feature, structure, or characteristic is not required to be included. If the specification or claim refers to “a” or “an” element, that does not mean there is only one of the element. If the specification or claims refer to “an additional” element, that does not preclude there being more than one of the additional element.
The inventions are not restricted to the particular details listed herein. Indeed, those skilled in the art having the benefit of this disclosure will appreciate that many other variations from the foregoing description and drawings may be made within the scope of the present inventions. Accordingly, it is the following claims including any amendments thereto that define the scope of the inventions.
Claims
1. A chip comprising:
- a transmitter including:
- encoding controlled frequency output circuitry to receive at least one input signal and at least one clock signal and to create a magnitude encoded controlled frequency signal (CFS) responsive thereto, wherein the CFS has values encoded in its magnitude and has substantially all of its energy restricted to a single frequency.
2. The chip of claim 1, wherein the encoding controlled frequency output circuitry is first encoding controlled frequency output circuitry and wherein the transmitter further comprises second encoding controlled frequency output circuitry to receive at least one input signal and at least one clock signal and to create a complementary magnitude encoded controlled frequency signal (CCFS) responsive thereto, wherein the CCFS has values encoded in its magnitude and has substantially all of its energy restricted to a single frequency.
3. The chip of claim 2, wherein the CFS and CCFS are encoded according to in phase magnitude encoding and wherein the magnitudes of the CFS and CCFS change with time.
4. The chip of claim 3, wherein the first and second encoding controlled frequency output circuitry each receive only one clock signal and the clock signal is the same for the first and second encoding controlled frequency output circuitry, and wherein the first and second encoding controlled frequency output circuitry each receive only one input signal and the input signal received by the first encoding controlled frequency output circuitry is a logical inverse of the input signal received by the second encoding controlled frequency output circuitry.
5. The chip of claim 2, wherein the CFS and CCFS are encoded according to power balanced magnitude encoding.
6. The chip of claim 5, wherein the first and second encoding controlled frequency output circuitry each receive only one input signal and the input signal is the same for the first and second encoding controlled frequency output circuitry, and wherein the first and second encoding controlled frequency output circuitry each receive only one clock signal and the clock signal received by the first encoding controlled frequency output circuitry is a logical inverse of the clock signal received by the second encoding controlled frequency output circuitry.
7. The chip of claim 2, wherein the CFS and CCFS are encoded according offset balanced magnitude encoding.
8. The chip of claim 7, wherein the first and second encoding controlled frequency output circuitry each receive two input signals that are logical inverses of each other, and wherein the first and second encoding controlled frequency output circuitry each receive only one clock signal and the clock signal received by the first encoding controlled frequency output circuitry is a logical inverse of the clock signal received by the second encoding controlled frequency output circuitry.
9. The chip of claim 2, further comprising a receiver to receive the CFS and CCFS and decode them to produce an output signal.
10. The chip of claim 9, further comprising additional transmitters and additional receivers.
11. The chip of claim 2, wherein the first and second encoding controlled frequency output circuitry each include a magnitude encoder, a controlled frequency driver, and magnitude drivers coupled to the magnitude encoder, and wherein the controlled frequency driver and the magnitude drivers combine to provide the respective CFS or CCFS on a conductor.
12. The chip of claim 11, wherein the magnitude drivers include more than two encode drivers.
13. The chip of claim 1, wherein the encoding controlled frequency output circuitry includes a magnitude encoder, a controlled frequency driver, and magnitude drivers coupled to the magnitude encoder, and wherein the controlled frequency driver and the magnitude drivers combine to provide the CFS on a conductor.
14. The chip of claim 1, further comprising a receiver to receive the CFS and decode it and produce an output signal responsive thereto.
15. A system comprising:
- a first chip including a transmitter including:
- encoding controlled frequency output circuitry to receive at least one input signal and at least one clock signal and to create a magnitude encoded controlled frequency signal (CFS) responsive thereto; and
- a second chip including a receiver to receive the CFS and to provide an output signal responsive thereto, wherein the CFS has values encoded in its magnitude and has substantially all of its energy restricted to a single frequency.
16. The system of claim 15, wherein the output signal is a time delayed version of the input signal.
17. The system of claim 15, wherein the output signal is a logical inversion of a time delayed version of the input signal.
18. The system of claim 15, wherein the first and second chips are coupled through a first conductor that carries the CFS to the receiver.
19. The system of claim 15, wherein the first and second chips are coupled through a first wave guide that carries the CFS to the receiver.
20. The system of claim 15, wherein the CFS is transmitted as an RF signal between the first and second chips.
21. A system comprising:
- a first chip including a transmitter including:
- first encoding controlled frequency output circuitry to receive at least one input signal and at least one clock signal and to create a magnitude encoded controlled frequency signal (CFS) responsive thereto; and
- second encoding controlled frequency output circuitry to receive at least one input signal and at least one clock signal and to create a complementary magnitude encoded controlled frequency signal (CCFS) responsive thereto; and
- a second chip including a receiver to receive the CFS and CCFS and to provide an output signal responsive thereto, wherein the CFS and CCFS each have values encoded in their magnitudes and have substantially all of their energy restricted to a single frequency.
22. The system of claim 21, wherein the output signal is a time delay version of the input signal.
23. The system of claim 21, wherein the output signal is an inversion of a time delay version of the input signal.
24. The system of claim 21, wherein the first and second chips are coupled through a first conductor that carries the CFS to the receiver and a second conductor that carries the CCFS to the receiver.
25. The system of claim 24, wherein the first chip also includes a receiver and the second chip also includes a transmitter.
26. The system of claim 24, wherein the first and second conductors are bi-directional.
27. The system of claim 21, wherein the first and second chips are coupled through a first wave guide that carries the CFS to the receiver and a second waveguide that carries the CCFS to the receiver.
28. The system of claim 21, wherein the CFS and CCFS are transmitted as RF signals between the first and second chips.
3665474 | May 1972 | Thayer |
4569017 | February 4, 1986 | Renner et al. |
4663767 | May 5, 1987 | Bodlaj et al. |
5103463 | April 7, 1992 | Schoeneberg |
5317597 | May 31, 1994 | Eisele |
5347543 | September 13, 1994 | Lecoco et al. |
5491434 | February 13, 1996 | Harnishfeger et al. |
5519526 | May 21, 1996 | Chua et al. |
5623518 | April 22, 1997 | Pfiffner |
5821779 | October 13, 1998 | Martwick |
5862180 | January 19, 1999 | Heinz |
5898735 | April 27, 1999 | Yamauchi |
6154498 | November 28, 2000 | Dabral et al. |
6693917 | February 17, 2004 | Feldman et al. |
6873829 | March 29, 2005 | Jeung |
0 110 427 | June 1984 | EP |
0 917 324 | May 1999 | EP |
- Zhang Jianfeng et al., DC-balanced line encoding for optical labeling scheme using orthogonal modulation; Research Center COM, Technical University of Denmark, 2003 Optical Sociaty of America; pp. 1-3.
- COUCH—Digital and Analog Communication Systems, pp. 160-169, 337-352, and 487-495 (Prentice Hall, 2001, 1997).
- P14339 PCT Search Report.
- PCT International Preliminary Examination Report.
- PCT Written Opinion Dated Nov. 22, 2004.
Type: Grant
Filed: Aug 21, 2002
Date of Patent: May 29, 2007
Patent Publication Number: 20040037362
Assignee: Intel Corporation (Santa Clara, CA)
Inventors: Jed D. Griffin (Forest Grove, OR), Jerry G. Jex (Olympia, WA), Brett A. Prince (Beaverton, OR), Keith M. Self (Aloha, OR)
Primary Examiner: Mohammed Ghayour
Assistant Examiner: Cicely Ware
Attorney: Blakely, Sokoloff, Taylor & Zafman LLP
Application Number: 10/226,074
International Classification: H04L 27/00 (20060101); H04L 7/00 (20060101); H04L 5/14 (20060101); H04B 1/00 (20060101);